Code Editor

<!DOCTYPE html>
<html>
<head><title>My Page</title></head>
<body>
  <h1>Hello World!</h1>
  <p>Welcome to my webpage.</p>
</body>
</html>

body {
  font-family: Arial, sans-serif;
  padding: 20px;
}
h1 {
  color: #3498db;
}

document.querySelector('h1').onclick = function () {
  this.style.color = '#' + Math.floor(Math.random()*16777215).toString(16);
};

Preview